The present invention relates to an improved method and apparatus for removing trash from material. More particularly, the present invention relates to a method and apparatus for removing heavy trash from formerly waste material containing trash, cotton lint, and motes.
During cotton ginning and early textile mill processing, a substantial quantity of good fiber is usually discarded with the trash. Much of this cotton fiber is contained in cotton motes. Cotton motes are those cotton fiber aggregates which are sufficiently dense to be discarded with the trash in conventional cleaning processes. The trash includes such particles as stems, burrs, leaf particles, etc. In order to more effectively utilize the fiber contained within the waste material, it is necessary to remove a substantial quantity of the heavy trash before attempting any further processing of the material.
A device for drying and cleaning cotton is disclosed in U.S. Pat. No. 1,449,392, issued Mar. 27, 1923 to Freeman. The Freeman patent discloses a rotatable drum surrounded on an outside periphery by a screen. Longitudinal reinforcing ribs are disposed along the inner periphery of the screen from one end to the other of the drum. The ribs are held against the inner surface of the screen by brace rings which are arranged further inside the drum. In addition, a plurality of equally spaced longitudinal truss rods extend along the inside surface of the drum. A plurality of fingers are threaded through the mesh of the screen and looped around the ribs with one end of the finger extending inwardly and being angled in the direction of the rotation of the drum.
It is submitted that an apparatus of the type disclosed in the Freeman patent produces a continuous rolling action rather than a cyclical lifting and dropping. This rolling action is due in part to the number of fingers contained within the drum of the Freeman patent. In other words, each longitudinal row of fingers picks up a small portion of the cotton and lifts the cotton toward the upper portion of the drum. This cotton is subsequently dropped toward the lower portion of the drum which is likely to be covered with cotton dropped by the immediately preceding longitudinal row of fingers.
In addition, a device of this type includes reinforcing ribs inside the screen such that the cotton cannot be dropped directly onto the screen to produce a vibratory action which aids in breaking up clusters of material. In other words, the cotton is likely to be dropped upon the ribs and then falls gently onto the screen rather than impacting directly on the screen. Still further, masses of cotton may become stagnant or stuck between each of the ribs and may not be affected by the rotation of the drum and lifted by the fingers. Further, due to the angled orientation of the fingers in the direction of rotation in the Freeman patent, cotton may be dropped along the back side of the fingers preventing a pulling action from being imparted by the fingers.
It is an object of the present invention to provide a method and apparatus which will effectively separate the heavy trash from waste material discarded by cotton gin and early textile mill processing.
It is a further object of the present invention to provide an apparatus which removes heavy trash and is simple in operation and construction and can be easily installed in existing cotton processing plants.
Still a further object of the present invention is to provide an apparatus for removing trash that can be operated for long periods of time without requiring stopping for cleaning or other maintenance.
These and other objects of the present invention are satisfied by providing an elongated drum with a plurality of finger-shaped baffles arranged on an inner periphery of the drum. An interior of the drum is surrounded by a screen having a small opening size to permit the heavy trash to fall through while retaining the motes and some lighter trash. The baffles are the only structual elements extending inwardly of the screen. In other words, any stiffening arrangement provided for maintaining the screen relatively rigid are arranged at a distance from a longitudinal axis of the drum which distance is at least equal to the distance of the screen from the axis. The drum is slowly rotated in order to lift the material to an upper portion of the drum with the finger-shaped baffles and drop the material onto the screen at a lower portion of the drum. This lifting and dropping action combined with the rotation of the drum acts similar to a vibratory action and tends to separate the trash from the material.
According to a further aspect of the present invention, an arrangement for continuously clearing material from openings in the screen is provided. In a preferred embodiment, the arrangement includes a brush which is arranged at a location on an outside surface of the drum which location is beyond the location where the baffles drop the material in the direction of rotation of the drum. The brush is arranged such that an outer peripheral surface of the brush contacts an outer surface of the screen. In a preferred embodiment, the brush is rotated about a longitudinal axis which is parallel with the longitudinal axis of the drum. The peripheral speed of rotation of the brush is preferably greater than the outer peripheral speed of the drum, particularly when the brush is rotated in the same direction of rotation as the drum.
Still further according to the present invention, the baffles are arranged in two to four rows with the baffles of each row extending along radii of the drum and being parallel to one another. Preferably, the rows are arranged symmetrically about the inside periphery of the drum. According to a still further aspect of the present invention, a plurality of rod-like elements for breaking up large clumps or portions of the material are provided on an inside surface of the drum. The rod-like elements are substantially shorter than the finger-shaped baffles such that the rod-like elements function to break up clumps or large portions of material rather than producing a substantial lifting and dropping action as do the finger-shaped baffles. The rod-like elements are preferably arranged in rows circumferentially spaced from the rows of the baffles with each rod-like element being arranged between adjacent ones of the finger-shaped baffles along the longitudinal axis of the drum.
It is further preferred that two rotating drums be provided to increase the efficiency of the apparatus. Also, the trash which drops through the screen is picked up by a conveyor and delivered to a trash disposal system. The present invention may be useful in a method and apparatus of the type disclosed in U.S. Pat. No. 4,300,267 issued Nov. 17, 1981 to Winch et al. for "Total Fiber Recovery Method and Apparatus".